Update selenium-webdriver dependency to 2.48

Author: bootstraponline

appium_lib.gemspec

@@ -14,7 +14,7 @@ Gem::Specification.new do |s|
   s.homepage      = 'https://github.com/appium/ruby_lib' # published as appium_lib
   s.require_paths = ['lib']
 
-  s.add_runtime_dependency 'selenium-webdriver', '~> 2.45'
+  s.add_runtime_dependency 'selenium-webdriver', '~> 2.48'
   s.add_runtime_dependency 'awesome_print', '~> 1.6'
   s.add_runtime_dependency 'json', '~> 1.8'
   s.add_runtime_dependency 'toml', '~> 0.0'